New issue
Advanced search Search tips

Issue 870612 link

Starred by 2 users

Issue metadata

Status: Unconfirmed
Owner: ----
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: Chrome
Pri: 2
Type: Bug



Sign in to add a comment

Synthesia app not finding connected digital piano

Project Member Reported by nakulj@google.com, Aug 3

Issue description

UserAgent: Mozilla/5.0 (X11; CrOS x86_64 10895.10.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.21 Safari/537.36
Platform: 10575.58.0 (Official Build) stable-channel eve

Steps to reproduce the problem:
1. Install Synthesia (https://play.google.com/store/apps/details?id=com.synthesia.synthesia&hl=en_US)
2. Connect Pixelbook to piano via a USB-C OTG adapter
3. Open Synthesia and follow the settings at https://www.synthesiagame.com/keyboards/Help/android/usb

What is the expected behavior?
A pop-up should appear, requesting permission for Synthesia to access the piano. Then, the piano should appear in the MIDI device list.

What went wrong?
Nothing happens. I know that this isn't a bug in Synthesia, or an issue with my cables- because when I follow the above steps using my android phone, it works perfectly. For some reason, the same android app on my Pixelbook can't find the device.

Did this work before? N/A 

Chrome version: 67.0.3396.99  Channel: stable
OS Version: 10575.58.0
Flash Version:
 
Cc: jhorwich@chromium.org lgcheng@google.com
Components: Platform>Apps>ARC
Long, this is ARC++ and USB related. Can you take a look?
Looks the app is using Android Usb Host mode. So it's something we are working on.

There are two type of issue here.
1. We are still not officially support Android Usb Host mode(https://developer.android.com/guide/topics/connectivity/usb/host) now. We have created private APIs for partners to access attached USB device, but public Android APIs are not working. We are working on support Android public USB host APIs for Android Q. 
It seems the app is using USB host APIs without declaring using this feature in manifest, as we are not declaring Android Usb Host support for Chromebooks yet.

2. Even after we officially support Android Usb Host mode, the device may be blacklist by ChromeOS so Android container still can't access the device.
detail can be found at:
https://bugs.chromium.org/p/chromium/issues/detail?id=148836

one simple test is to install extension from chrome store https://chrome.google.com/webstore/detail/usb-device-info/igkmggljimacfdfalpeelenjeicmfnll?utm_source=chrome-app-launcher-info-dialog  
to see if the device can be listed in the extension.

For the second issue we don't have any plan yet.
I contacted the app developers and they told me to try their beta channel. Interestingly, that worked perfectly.

Hopefully that will continue to work in the future?
Did their app work on you pixelbook with your midi keyboard connected via usb?

When the app request for USB permissions, is it a regular Android dialog or something else? Would you send a screenshot of the permission dialog if possible?

We did create private api for partners for USB access, but that's not something public at all, and I doubt app developers know how to use those private apis.




Yes. The setup was- midi keyboard -> USB B male to USB A male cable -> USB A-C OTG adapter, Pixelbook

I don't remember what the permission dialog was. I don't think there was one at all, I just remember plugging it in and it working right away. Any way I can check?

You can also just try the beta version of the app and see what happens.

Sign in to add a comment